Cut the stewing beef into large pieces and toss with flour.
In a large pot sear the beef with a drizzle of olive oil and set aside.
In the same pan add a fresh drizzle of olive oil if necessary and sweat the onion. Once the onion is soft add the red peppers and garlic. Allow to cook until the peppers have softened, about 5 minutes.
For the goulash
Add the tomato paste and cook for an additional 2-3 minutes.
Finally add the paprika, crushed tomatoes and stock. Stir well and bring to a gentle simmer.
Put the lid on the pot and place in the oven for 1.5 hours or until the beef is tender.
Remove from the oven and add the mushrooms.Place on a low burner and reduce until the goulash thickens.